Climate and Average Weather Year Round in Sisimiut Greenland

In Sisimiut, the summers are cold and mostly cloudy and the winters are frigid, snowy, windy, and overcast. Over the course of the year, the temperature typically varies from 2°F to 51°F and is rarely below -16°F or above 57°F.

Based on the tourism score, the best time of year to visit Sisimiut for warm-weather activities is from mid to late July.

The warm season lasts for 3.2 months, from June 5 to September 12, with an average daily high temperature above 43°F. The hottest month of the year in Sisimiut is July, with an average high of 50°F and low of 41°F.

The cold season lasts for 3.3 months, from December 20 to March 30, with an average daily high temperature below 18°F. The coldest month of the year in Sisimiut is February, with an average low of 2°F and high of 11°F.

In Sisimiut, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Sisimiut begins around April 11 and lasts for 6.9 months, ending around November 7.

The clearest month of the year in Sisimiut is June, during which on average the sky is clear, mostly clear, or partly cloudy 40% of the time.

The cloudier part of the year begins around November 7 and lasts for 5.1 months, ending around April 11.

The cloudiest month of the year in Sisimiut is January, during which on average the sky is overcast or mostly cloudy 85% of the time.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Sisimiut varies throughout the year.

The wetter season lasts 7.2 months, from April 27 to December 2, with a greater than 18% chance of a given day being a wet day. The month with the most wet days in Sisimiut is August, with an average of 8.4 days with at least 0.04 inches of precipitation.

The drier season lasts 4.8 months, from December 2 to April 27. The month with the fewest wet days in Sisimiut is February, with an average of 2.3 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation in Sisimiut changes throughout the year.

Snow alone is the most common for 6.0 months, from October 25 to April 26. The month with the most days of snow alone in Sisimiut is November, with an average of 3.6 days.

Rain alone is the most common for 6.0 months, from April 26 to October 25. The month with the most days of rain alone in Sisimiut is August, with an average of 8.4 days.

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Sisimiut experiences significant seasonal variation in monthly rainfall.

The rainy period of the year lasts for 7.2 months, from April 19 to November 26, with a sliding 31-day rainfall of at least 0.5 inches. The month with the most rain in Sisimiut is August, with an average rainfall of 2.4 inches.

The rainless period of the year lasts for 4.8 months, from November 26 to April 19. The month with the least rain in Sisimiut is January, with an average rainfall of 0.1 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Sisimiut experiences significant seasonal variation in monthly snowfall.

The snowy period of the year lasts for 8.0 months, from September 28 to May 28, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Sisimiut is November, with an average snowfall of 6.8 inches.

The snowless period of the year lasts for 4.0 months, from May 28 to September 28. The least snow falls around August 16, with an average total accumulation of 0.0 inches.

Due to its extreme latitude, Sisimiut experiences polar day (also known as the midnight Sun) during the summer. The precise start and end dates of polar day and night vary from year to year and depend on the precise location and elevation of the observer, and the local topography.

In the summer in Sisimiut during 2024, the Sun is continuously above the horizon for 1.3 months, rising at 2:54 AM on June 1, and not setting again until 2:27 AM on July 10.

Daylight saving time (DST) is observed in Sisimiut during 2024, starting in the spring on March 31, lasting 6.9 months, and ending in the fall on October 26.

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The perceived humidity level in Sisimiut, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, remaining a virtually constant 0% throughout.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Sisimiut experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 7.4 months, from September 28 to May 9, with average wind speeds of more than 9.0 miles per hour. The windiest month of the year in Sisimiut is December, with an average hourly wind speed of 10.6 miles per hour.

The calmer time of year lasts for 4.6 months, from May 9 to September 28. The calmest month of the year in Sisimiut is July, with an average hourly wind speed of 7.2 miles per hour.

The predominant average hourly wind direction in Sisimiut varies throughout the year.

The wind is most often from the south for 1.4 weeks, from August 1 to August 11, with a peak percentage of 37% on August 9. The wind is most often from the north for 12 months, from August 11 to August 1, with a peak percentage of 43% on January 1.

Sisimiut is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences some seasonal variation over the course of the year.

The time of year with warmer water lasts for 2.5 months, from July 8 to September 23, with an average temperature above 39°F. The month of the year in Sisimiut with the warmest water is August, with an average temperature of 41°F.

The time of year with cooler water lasts for 5.5 months, from November 28 to May 11, with an average temperature below 33°F. The month of the year in Sisimiut with the coolest water is February, with an average temperature of 31°F.

To characterize how pleasant the weather is in Sisimiut throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Sisimiut for general outdoor tourist activities is from mid to late July, with a peak score in the third week of July.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Sisimiut typically lasts for 3.3 months (102 days), from around June 12 to around September 22, rarely starting before May 24 or after July 4, and rarely ending before September 3 or after October 10.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 2.6 months, from May 6 to July 27, with an average daily incident shortwave energy per square meter above 4.6 kWh. The brightest month of the year in Sisimiut is June, with an average of 5.8 kWh.

The darker period of the year lasts for 5.0 months, from October 6 to March 5, with an average daily incident shortwave energy per square meter below 1.2 kWh. The darkest month of the year in Sisimiut is December, with an average of 0.0 kWh.

For the purposes of this report, the geographical coordinates of Sisimiut are 66.939 deg latitude, -53.674 deg longitude, and 20 ft elevation.

The topography within 2 miles of Sisimiut contains very significant variations in elevation, with a maximum elevation change of 1,549 feet and an average elevation above sea level of 204 feet. Within 10 miles contains very significant variations in elevation (2,398 feet). Within 50 miles contains large variations in elevation (5,971 feet).

The area within 2 miles of Sisimiut is covered by sparse vegetation (36%), snow and glaciers (25%), and grassland (24%), within 10 miles by water (48%) and snow and glaciers (21%), and within 50 miles by water (52%) and sparse vegetation (14%).